Lubricating structure for outboard motors

Abstract

There is provided a lubricating structure for an outboard motor, which can secure a sufficiently large cross-sectional area for a main oil gallery while preventing an increase in the width of an engine thereof. A water-cooled four-cycle six-cylinder V-type engine having a generally vertically disposed crankshaft is mounted on an engine holder. A cylinder block is disposed at the rear of a crankcase disposed in the foremost end (i.e. on the bow side) of the engine, and a main oil gallery extends vertically in the starboard-side side part of the cylinder block. Namely, the main oil gallery is disposed not in a central part of the cylinder block in the transverse direction thereof, but at a location outward of cylinder bores of the cylinder block.

1. A lubricating structure for an outboard motor, comprising:
 a vertically installed V-type engine having a side part; 
 a main oil gallery formed in said side part of said engine, for allowing lubricating oil to pass therethrough; and 
 an oil gallery formed substantially in a central part of said engine in a transverse direction of said engine, as a passage separate from said main oil gallery, for allowing oil for cooling pistons to pass therethrough. 
 
     
     
       2. A lubricating structure as claimed in  claim 1 , comprising an oil filter disposed in said side part of said engine at a location close to said main oil gallery in a fashion directly connected thereto, for filtering the lubricating oil. 
     
     
       3. A lubricating structure as claimed in  claim 1 , comprising a coolant passage formed in said engine at a location close to said oil gallery, for cooling said oil gallery. 
     
     
       4. A lubricating structure for an outboard motor, comprising:
 a vertically installed V-type engine including a cylinder block having a bottom part and an oil filter; 
 an oil passage formed in said bottom part of said cylinder block; and 
 a supply passage extending to said oil filter and a return passage extending from said oil filter, said supply passage and said return passage being formed by partitioning said oil passage. 
 
     
     
       5. A lubricating structure as claimed in  claim 4 , comprising a lid assembly, and
 wherein at least one of said supply passage and said return passage has a part thereof formed by casting and covered by said lid assembly to form a passage. 
 
     
     
       6. A lubricating structure as claimed in  claim 4 , comprising a lid assembly, and
 wherein one of said supply passage and said return passage has a part thereof formed by casting and covered by said lid assembly to form a passage, and the other of said supply passage and said return passage is formed in said lid assembly. 
 
     
     
       7. A lubricating structure as claimed in  claim 4 , comprising a plurality of distribution passages in communication with said return passage, for distributing oil to component parts of said engine. 
     
     
       8. A lubricating structure for an outboard motor, comprising:
 a cylinder block; 
 a cylinder head having an oil passage formed therein; 
 a hydraulically driven variable valve timing mechanism; 
 an oil pump for supplying oil under pressure, the oil supplied under pressure from said oil pump being supplied as driving oil to said variable valve timing mechanism from said cylinder block through said oil passage formed in said cylinder head, and supplied as lubricating oil to said cylinder head; and 
 at least one first passage and at least one second passage formed as passages separate from each other in said cylinder block, for guiding the oil supplied under pressure from said oil pump to said cylinder head; 
 wherein said cylinder block has at least one head-lubricating oil hole formed therein, for supplying the oil supplied through said first passage formed in said cylinder block to component parts within said cylinder head, as lubricating oil; and 
 wherein said cylinder block has at least one mechanism-driving oil hole formed therein, as a passage separate from said head-lubricating oil hole, for supplying the oil supplied through said second passage formed in said cylinder block to said variable valve timing mechanism, as driving oil.